Mustafa Abdel Jalil, chairman of the National Transitional Council (NTC), had been expected to announce a cabinet of up to 36 members in an effort to emphasise unity and counter criticism that the body was unrepresentative.
But a failure to reach agreement appears to reflect divisions that are casting a shadow over the post-revolutionary political landscape. Mahmoud Jibril, the acting prime minister, would only say consultations in Benghazi had not been completed, but NTC sources said they believed a deal would be done "within days".
The NTC has been under pressure to appoint some Islamist figures to reflect their role in the revolution, but tensions have emerged between the council and rebel commanders, as well as with Ali Salabi, an influential preacher being promoted by Qatar and its al-Jazeera TV channel.
Rebels in the former enclave of Misrata, who took heavy losses during the revolution, announced their own candidate, Abdul-Rahman Sweilhi, for prime minister. Sweilhi warned of the danger of a "new dictatorship" and insisted the government could not include "symbols of the Gaddafi regime".